1. Field of the Invention
The present invention relates to coffee mills and to coffee-making machines for professional use. The machines are equipped with said mills and the lower portion of each mill is provided with a station for pouring the coffee powder into a brewing receptacle.
2. Description of the Prior Art
Coffee mills of this type are so designed as to be capable of delivering at the start of each operation the dose of coffee powder which is necessary for making a quantity of coffee-brew corresponding to one or a number of cups.
However, coffee mills of this type which are in current use are subject to a certain number of drawbacks.
The chief drawback lies in the fact that, by reason of their design concept, there always exists a reserve quantity consisting of one or a number of doses of coffee powder in the different parts of a mill of this type and in the ducts through which the powder is discharged. When a fresh quantity of coffee is being ground, the powder thus produced pushes the previously ground coffee into a fixed distribution cylinder and is left in the waiting state within the coffee mill until another dose of powder in turn thrusts it forward. The disadvantage of this process is that a coffee-brewing operation is carried out each time with a dose of powder which had been allowed to remain in the waiting state and not with freshly ground powder. The coffeebrew obtained is consequently not of good quality.
Moreover, taking into account the possibilities of stagnation of a certain quantity of powder within the discharge ducts and other passages, the dose of powder delivered into the coffee receptacle is inaccurate and this also impairs the quality of the coffee-brew. A further disadvantage which arises from stagnation of coffee powder within the discharge ducts and other passages is that they must consequently be cleaned periodically, thus requiring the services of a specialized technician. It should be added that the danger of clogging is particularly great when a coffee mill is provided with a distribution cylinder.
There was described in French Patent No. 2,074,679 a coffee mill in which two grades of coffee are present within the machine and in which either one grade or the other can be ground according to choice. Provision is accordingly made for two grinding units disposed along two parallel horizontal axes and for a vertical reception duct, the axis of which is located in the vertical mid-plane between the two grinding units. In addition, these two grinding units are driven by a single motor, preselecting means being so arranged that only one of the two grinding units is active when the motor is started-up. However, in this patent, the ground coffee is poured into a vertical feedpipe which opens onto a distribution plate, with the result that the coffee powder is thrust in the upward direction. As already mentioned, this device consequently has a disadvantage in that a coffee infusion or "brew" is made with a dose of powder which had been left in the waiting state and not with freshly ground powder.
Furthermore, when changing-over from one grinding unit to the other in order to change to a different grade of coffee, several qualities of ground coffee powder are present in the waiting condition within the feedpipe, thus making a machine of this type extremely inconvenient to use.
The object of the present invention is to overcome the various disadvantages mentioned above by producing a coffee mill so designed as to ensure that the freshly ground powder is immediately employed for the preparation of a coffee infusion dose and that, in addition, there should be no danger of stagnation of powder within the coffee mill or within the discharge duct.